Hurricane IKE (Text)

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HURRICANE IKE DISCUSSION NUMBER 10
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092008
500 PM EDT WED SEP 03 2008
AS ANTICIPATED...IKE HAS CONTINUED TO STRENGTHEN AND ALL
SATELLITE-BASED ESTIMATES SAY IT HAS BECOME A HURRICANE. SINCE THE
1800 UTC DVORAK ESTIMATES OF 65 KT...AN EYE HAS BECOME APPARENT IN
LATE-DAY VISIBLE IMAGERY...SO THE INTENSITY IS SET TO 70 KT. THE
CYCLONE IS INTENSIFYING WITHIN A COCOON OF NEARLY ZERO VERTICAL
WIND SHEAR...IN BETWEEN THE DEEP-LAYER LOW OVER THE NORTHWESTERN
ATLANTIC AND AN UPPER-LEVEL TROUGH DOMINATING THE EASTERN PORTION
OF THE BASIN. WATER VAPOR IMAGERY REVEALS THAT THE UPPER-LEVEL
NORTHERLIES ALONG THE WESTERN FLANK OF THE EASTERN TROUGH ARE
STARTING TO JUST SLIGHTLY RESTRICT IKE'S OUTFLOW. GLOBAL MODELS
FORECAST THE SHEAR TO INCREASE FROM THE EAST...BUT PROBABLY NOT
QUICKLY ENOUGH TO HALT IKE'S INTENSIFICATION TREND IN THE SHORT
TERM. THE NEW OFFICIAL FORECAST SHOWS AN INTERMEDIATE INTENSITY
PEAK AT 24 HOURS PRIOR TO THE ONSET OF THE SHEAR...FOLLOWED BY
SLIGHT WEAKENING UNTIL THE SHEAR ABATES AFTER IKE GETS FARTHER
WEST. BY THAT TIME...IN ABOUT 72 HOURS...OCEAN AND ATMOSPHERIC
FACTORS BECOME QUITE CONDUCIVE FOR INTENSIFICATION...AND THE
DYNAMICAL MODELS GFDL AND HWRF...FORECAST A MAJOR HURRICANE BY DAYS
4 AND 5...WHICH IS ALSO SHOWN IN THE OFFICIAL FORECAST. LONG-RANGE
INTENSITY FORECASTS ARE RATHER UNCERTAIN...HOWEVER...AND THE
INTENSITY PROBABILITY TABLE INCLUDED IN THIS ADVISORY PACKAGE
INDICATES THAT THERE IS ROUGHLY A 50 PERCENT CHANCE THAT IKE WILL
BE A MAJOR HURRICANE FOUR AND FIVE DAYS FROM NOW. IF IKE IS WEAKER
THAN THE OFFICIAL FORECAST AT DAYS 3-5...THEN THE
STATISTICAL-DYNAMICAL MODELS SHIPS AND LGEM WILL TURN OUT TO BE
MORE ACCURATE.
THE HURRICANE CONTINUES HEADING WEST-NORTHWESTWARD OR 290/16. AS
THE LARGE AND DEEP-LAYER LOW CURRENTLY JUST OFF THE NORTHEAST
U.S. COAST DEPARTS TO THE NORTHEAST...MID-LEVEL RIDGING WILL BUILD
OVER THE WESTERN ATLANTIC...WHICH WILL PUSH IKE GENERALLY WESTWARD
DURING THE NEXT SEVERAL DAYS. UNDULATIONS IN THE TRACK ARE
LIKELY THOUGH. IKE SHOULD CONTINUE WEST-NORTHWESTWARD UNTIL THE
WESTERN ATLANTIC RIDGE FORMS...AFTER WHICH THE TROPICAL CYCLONE
WILL GRADUALLY ROUND THAT RIDGE. THE BIG QUESTION AT LONGER RANGES
IS IF AND WHEN IKE WILL ROTATE AROUND THE WESTERN PERIPHERY OF THAT
RIDGE...WHICH WILL DETERMINE WHETHER IKE DIRECTLY AFFECTS ANY LAND
AREAS. THE MODELS DO NOT PROVIDE AN UNANIMOUS ANSWER...WHICH IS
NOT SURPRISING THIS FAR IN ADVANCE. ALL OF THE MODELS DO SHOW THE
BEGINNINGS OF A MOTION NORTH OF DUE WEST BY DAY 5...BUT IT IS TOO
EARLY TO DETERMINE IF THIS IS THE START OF RECURVATURE...OR IF
ENOUGH RIDGING WILL REMAIN BEYOND DAY 5 TO KEEP IKE MOVING
GENERALLY WESTWARD.
FORECAST POSITIONS AND MAX WINDS
INITIAL 03/2100Z 21.6N 52.7W 70 KT
12HR VT 04/0600Z 22.6N 55.1W 75 KT
24HR VT 04/1800Z 23.8N 57.9W 85 KT
36HR VT 05/0600Z 24.3N 60.4W 80 KT
48HR VT 05/1800Z 23.8N 63.1W 80 KT
72HR VT 06/1800Z 22.5N 68.0W 90 KT
96HR VT 07/1800Z 22.5N 72.0W 100 KT
120HR VT 08/1800Z 23.5N 76.0W 100 KT
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FORECASTER KNABB
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